Field of Invention
The present invention relates to a profile structure of a meshing pair of a gear, and more particularly to a method for constructing a profile of two flanks of a star wheel tooth of a single-screw compressor.
Description of Related Arts
The single-screw compressor or pump (as showed in FIG. 1), comprising a single-screw rotor, two star wheels and a housing, is recognized as a rotary fluid machinery having an outstanding overall structure performance Since the advent of the single-screw compressor in France in 1960s, multiple single-screw compressors have entered the industrial market. In the major industrial nations in the world, multiple manufacturers have developed and manufactured the single-screw compressors in recent years. The meshing profiles of the star wheel of the single-screw compressor which is available in the market are single-edge line structured, namely that, on the meshing face of the flank of each star wheel tooth, the single edge line stretches from the tooth root to the tooth top along a radial direction. The edge line is the intersection line of two planes having the gradually varied inclined angle. In order to improve the wear-resistance of the profile, the Chinese patent applications, CN200610042414.1 and CN201010293319.X, respectively provide a method for designing a multi-column envelope profile and a method for designing a multi-column non-isometric milling envelope profile. The above two Chinese patent applications merely respectively illustrate that the profile of the front flank of the star wheel tooth is the three-column envelope surface and the profile of the back flank of the star wheel tooth is the three-column envelope surface, and also provide the representation formula of the three columns. However, the above two Chinese patent applications fail to collaboratively consider the profile of the front flank and the back flank of the star wheel tooth, and thus fail to establish the association condition and the association construction upon the mutual restriction and the mutual impact between the profile of the front flank and the back flank of the star wheel tooth. Actually, for the single-screw compressor under the given working condition, if the profile of the front flank and the back flank of the star wheel tooth are designed independently, the liquid film bearing performance between the two flanks of the star wheel tooth may has a great difference, causing the obvious abrasion on one of the two flanks.